An armed law enforcement officer on the campus where last week's Florida school shooting took place did nothing to stop the massacre, it has been revealed.
School resource officer Scot Peterson was "absolutely on campus through this entire event', said Broward County Sheriff Scott Israel on Friday (NZ Time).
"He was armed, he was in uniform," said Mr Israel, but video showed him waiting outside the school building despite "clearly" knowing what was going on inside.
"What I saw was a deputy arrive at the west side of building 12, take up a position, and he never went in," Mr Israel said.
A 19-year-old armed with an AR-15 assault rifle killed 17 people on Valentine's Day at Marjory Stoneman Douglas High School, setting off perhaps the most contentious debate on gun control the US has seen in years.
Mr Israel said the latest revelation made him "sick to my stomach".
"There are no words. I mean these families lost their children. I've been to the funerals. I've been to the vigils. There are no words."
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The revelation won't boost US President Donald Trump's call for teachers to be armed.
"If you had a teacher who is adept at firearms it could very well end the attack very quickly," he said on Thursday (NZ time).
"A gun-free zone to a killer, or somebody that wants to be a killer, that's like going in for the ice cream. They're not going to walk into a school if 20 percent of the teachers have guns."
The powerful National Rifle Association echoed Mr Trump's claims, chief executive Wayne LaPierre calling schools "soft targets for anyone bent on mass murder".
"The elites don't care not one whit about America's school system and school children. Their goal is to eliminate the Second Amendment and our firearms freedoms so they can eradicate all individual freedoms."
After the 2012 Sandy Hook school shooting, Mr LaPierre infamously said to "stop a bad guy with a gun, it takes a good guy with a gun".
Two other Broward County deputies are being investigated after evidence emerged they'd been told about the gunman's behaviour prior to the massacre, but nothing had been done.